The Universal Serial Bus (USB) is a serial bus standard for connecting a periphery device to a computer device, and is gradually replacing the serial or parallel ports of a computer device. With the development of USB technology, USB 2.0 and USB 1.1/1.0 are supported by the USB 3.0 interface. The USB 3.0 interface is designed to having 9 pins, wherein the USB 2.0 and USB 1.1/1.0 interfaces use the data transmission pins D+ and D− for data transmission, and USB 3.0 interface uses the data transmission pins Tx+, Tx−, Rx+ and Rx− for data transmission. Under this framework, the data transmission of the USB 2.0 interface and the data transmission of the USB 3.0 interface are independent and individual systems, and the data transmissions of the USB 3.0 and USB 2.0 do not influence each other. However, a USB port with the USB 3.0 interface is tested via a USB HUB to evaluate the USB 3.0, USB 2.0 and USB 1.1/1.0 function, such that the USB 3.0 interface and USB 2.0 interface are tested at the same time (i.e., the USB HUB is provided with a device module with the USB 3.0 interface and a device module with the USB 2.0 interface), whereby a computer device may easily crash or cause error. Therefore, testing for a single USB port of a computer or notebook has to use many USB testing devices individually for different USB interfaces.